The present invention relates to a semiconductor device and an operating method thereof, and more particularly to a semiconductor device for reducing current consumption using dummy cells and an operating method thereof.
A semiconductor device includes a memory cell array for storing data. The memory cell array has cell blocks. Each of the cell blocks includes cell strings. Each of the cell strings comprises a drain select transistor, memory cells, and a source select transistor coupled in serial. Recently, dummy cells are coupled between the memory cells and the drain or source select transistor to prevent leakage by hot carrier capable of generating in a program operation.
The semiconductor device further includes dummy lines for controlling the dummy cells included in each of the cell strings. Thus, a voltage for controlling the dummy lines is required when the semiconductor device operates. Particularly, when the semiconductor device operates, an operation voltage should be applied to a drain dummy line coupled to drain dummy cells of each of the cell strings to control the drain dummy cells coupled between the memory cells and the drain select transistor. An operation voltage should be provided to a source dummy line coupled to source dummy cells of each of the cell strings to control the source dummy cells coupled between the memory cells and the source select transistor.
As described above, since the dummy cells prevent leakage by the hot carrier, a pass voltage is applied to the drain dummy lines and the source dummy lines. Accordingly, the dummy cells do not involved with an operation such as a program operation, a read operation, or an erase operation. Generally, the pass voltage is in approximately 4.5V in the read operation and about 9V in the program operation. The pass voltage may be set differently according to operational condition of the semiconductor device, but has usually higher voltage level than a supply voltage. Accordingly, much current is consumed if the pass voltage is applied to every dummy line whenever the program operation, the read operation, or the erase operation is performed.
Recently, the number of the cell strings has increased according as the number of the memory cells included in the memory cell array augments. As a result, malfunction of the semiconductor device may occur due to interference between adjoining cell strings. Accordingly, when the program operation, the read operation or the verifying operation is performed, the cell strings are divided into an even cell string group and an odd cell string group. One of the even cell string group and the odd cell string group is selected, and corresponding operation is performed in the selected cell string group. Then, corresponding operation to the other cell string group is performed. In case when even cell strings are selected and odd cell strings are not selected, current path of odd bit lines coupled to the odd cell strings is blocked not to select the odd cell strings. Current paths between page buffers and the odd bit lines are also blocked. This method just blocks the current path between the page buffers and the odd bit lines, for not selecting the odd cell strings. However, the method does not itemize or differentiate operations of the even cell strings and the odd cell strings each other. Accordingly, efficiency of the operation may lower when operating separately the cell strings.